Patrick Olguin schreef
Even these might not help all that much, seeing
as you're using purpleheart. This wood is not only hard, it's full of
silica [...]

PvR states:
Nope. It isn't. Not resistant to teredo either

Charlie Self schreef
According to William Lincoln, it exudes a gummy residue if heated by dull
tools. Might be messy.

+ + +
That is possible, but only if the relevant tree was damaged during its life.
It is not the rule.
+ + +

I've always made sure tools for purpleheart are
especially sharp. While teredo (shipworm) is not a particular problem
outside oceans (docks, ships, boats, similar structures), powder post beetle
can chew up the sapwood.

+ + +
Sapwood is never resistant to anything, no matter what wood you are talking
about ...
PvR